1. Field of the Invention
The present invention relates to an injection molding machine in which melted resin is injected from an injection apparatus and charged into a mold in order to mold a product.
2. Description of the Related Art
The basic configuration of a conventional inline-screw-type injection molding machine is disclosed in, for example, Japanese Patent Application Laid-Open (kokai) No. 9(1997)-109221. In such an injection molding machine, a mold clamping apparatus is disposed on one side of an upper surface of a machine base, and an injection apparatus is disposed on the other side of the upper surface of the machine base via an injection-apparatus reciprocation drive section. For a nozzle touch operation, the injection apparatus is advanced by the injection-apparatus reciprocation drive section, so that the tip end of an injection nozzle is brought into pressing contact with a mold (stationary mold) fixed to a mold attachment plate (stationary plate). For a nozzle release operation, the injection apparatus is retracted by the injection-apparatus reciprocation drive section, so that the tip end of the injection nozzle is separated from the mold.
Incidentally, since resin of high pressure is charged into the cavity of the mold, for the nozzle touch operation, a predetermined pushing force must be applied to the injection nozzle in order to bring the injection nozzle into pressing contact with the mold (stationary mold) supported by the mold attachment plate. In the conventional injection molding machine, the bottom portions of the mold attachment plate and the injection apparatus are fixed to or supported by the upper surface of the machine base, and when a large pushing force is applied horizontally to the mold attachment plate and the injection apparatus, the mold attachment plate and the injection-apparatus reciprocation drive section are subjected to excessive stresses, resulting in inclination of the mold attachment plate and/or the injection apparatus, a decrease in durability, occurrence of a malfunction, and additional cost for securing mechanical strength.
An object of the present invention is to provide an injection molding machine whose mechanical strength (fixation strength) has been increased greatly in order to prevent inclination of a mold attachment plate and/or an injection apparatus to thereby improve durability and prevent occurrence of a malfunction.
Another object of the present invention is to provide an injection molding machine employing tie-bars which provide various functions in order to reduce cost and to eliminate an additional cost which would otherwise be required to secure a sufficient mechanical strength of a mechanism for fixing or supporting the mold attachment plate and the injection apparatus.
To achieve the above objects, the present invention provides an injection molding machine which is equipped with an injection apparatus support mechanism comprising at least one main tie-bar disposed to extend between a mold attachment plate and a back plate disposed to face each other; front and rear support plates connected to each other via at least one auxiliary tie-bar and slidably supported by the main tie-bar; and an intermediate support block slidably supported by the main and auxiliary tie-bars, and in which a barrel is provided on the front support plate; a screw rotation drive section for rotating a screw inserted into the barrel is provided on the intermediate support block; a screw reciprocation drive section for advancing and retracting the screw rotation drive section is provided on the rear support plate; and an injection-apparatus reciprocation drive section for advancing and retracting the rear support plate is provided on the back plate.
Since the mold attachment plate and the back plate are supported by the main tie-bar, preferably a pair of the main tie-bars disposed symmetrically with respect to the screw, a sufficient level of mechanical strength (fixation strength) is secured for the mold attachment plate and the back plate. In addition, since the front support plate and the rear support plate are connected to each other by the auxiliary tie-bar, preferably, a pair of the auxiliary tie-bars disposed symmetrically with respect to the screw at positions different from those of the main tie-bars, the mechanical strength of these plates is secured. In this case, since the main tie-bar supports (guides) the front and rear support plates, the main tie-bar provides a support function and a guide function for the front and rear support plates. In addition, since the main and auxiliary tie-bars support (guide) the intermediate support block, the main and auxiliary tie-bars provide a support function and a guide function for the intermediate support block. Meanwhile, since the rear support plate is advanced and retracted by the injection-apparatus reciprocation drive section provided on the back plate, a reaction force generated during nozzle touch operation acts on the back plate in a direction perpendicular thereto, so that no excessive stresses act on the mold attachment plate and the injection apparatus.